: The United States is facing the most critical and devastating epidemic in its recent history resulting from spread of the human immunodeficiency virus (HIV) and its resulting clinical complications, including acquired immune deficiency syndrome (AIDS). Nonhuman primates, phylogenetically our closest living relatives, have always been very important as models for studying human disease, as well as for testing drug therapies and vaccines. The preferred nonhuman primate model for AIDS and AIDS-related studies is the Indian-origin rhesus macaque (Macaca mulatta). It is now possible to conduct basic research on AIDS in these primates with a high degree of confidence that the results will be directly applicable to the human syndrome. Implicit in the development of nonhuman primate disease models is the notion that the recipient model must be completely free of viruses that could potentially compromise research. The National Institutes of Health (NIH) also recognizes that there is a special need for major histocompatibility complex (MHC) defined rhesus macaques for certain types of AIDS-related research. We propose two independent but complementary options through which LABS of Virginia, Inc., a long-term provider of SPF macaques to the biomedical research community, can provide the NIH with large numbers of Indian-origin SPF rhesus macaques and ensure the availability of Indian-origin rhesus macaque breeding stock to meet future research needs. Option #1 provides for purchase and maintenance of an SPF-pedigree breeding colony and up to 260 SPF- pedigree research offspring, and Option #2 provides for purchase and maintenance of a non-SPF breeding colony and up to 412 SPF-derived offspring. SPF is defined as serologically negative and virus culture negative for Herpesvirus simiae, simian immunodeficiency virus (SIV), simian T-lymphotropic virus (STLV-1), and Type D simian retrovirus (SRV: SRV1, SRV2, and SRV5). SPF-pedigree is defined as the offspring of SPF parents and SPF-derived is defined as the offspring of Non-SPF (but seronegative for SRV) parents. Implicit in this objective is management of the existing SPF rhesus macaque resource and development of additional animal resources, including selective breeding of MHC-defined rhesus (up to 140 over a five-year period).